This invention relates generally to a method for conditioning abrasive tools and more particularly to a method of conditioning superabrasive wheels.
Precision grinding is a known process used to form machined parts by rotating or otherwise moving an abrasive tool (e.g. a grinding wheel) at a high surface speed and feeding it into a workpiece. Common abrasive tools include aluminum oxide grit dispersed in a binder, for example. “Superabrasives” such as diamond or cubic boron nitride (CBN) have also been developed, which are much longer wearing than conventional abrasives and allow higher feed rates in hard materials.
Strict metallography requirements (e.g. low cycle fatigue and residual stress) have hampered or even prohibited the use of superabrasive grinding wheels for certain gas turbine engine components, because of the adverse post-dress condition of the superabrasive grinding wheel. After dressing or wheel truing the binder material that holds the superabrasive particles of the superabrasive grinding wheel fills the spaces between the superabrasive crystals, inhibiting good coolant and chip flow. This condition causes part material “burning” (i.e. localized overheating) to occur until the bond material erodes sufficiently to allow space for coolant and chips. This condition is especially sensitive to softer materials such as stainless steel (e.g. AM355 and A286 alloys). Prior art methods exist for “opening” the grinding wheel surface to expose the abrasive particles, however they are typically manual methods which are difficult to perform in a repeatable manner.
Accordingly, there is a need for a simple and repeatable method of conditioning a superabrasive tool to avoid localized workpiece overheating.